This document discusses Spectrum Virtualize throttling and summarizes the results of testing different throttling configurations on vdisks, hosts, and storage pools. Throttles can be set to limit bandwidth in MB/s or IOPS. Testing showed that the lowest throttle set on a parent storage pool or host would determine overall performance, and throttles on individual vdisks or child pools only limit bandwidth beyond the parent throttle. Response time was observed to increase when host throttles were configured.

1. SVC THROTTLING V7.8.1
Johan van Arendonk
jvarendonk@e-storage.nl

2. SPECTRUM VIRTUALIZE THROTTLING
© 2015 E-Storage All rights reserved
- Spectrum Virtualize 7.8.1.x offers the opportunity to do throttling on vdisks, host,
Hostcluster and mdiskgroups (pools and childpools)
- Throttling can be set on MB/sec and IO/sec.
- What is the impact when there throttles defined for hosts, vdisks and pools?
- When beloning together or not
- Is there impact on latency?
- What if you set a throttle of 100MB.. Is this read, write or a sum?
I did some small tests to find out what happens when working with these new throttles

3. V7000 Pool
SVC THROTTLING
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Scenario:
VDISK01
CG8-vdisk
- 25GB thin provisioned
- Same I/O Group
- Same Preferred Node
Win2012
wwpn
wwpn
V7000 Child Pool
VDISK02
CG8-vdisk
Host

4. TOTAL PERFORMANCE ON SVC (WITH IO-METER RUNNING ON WINDOWS HOST)
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MBps IOps
No IO –traffic to backend
No throttling

5. VDISK PERFORMANCE IO & DATA RATE
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No throttling set.
IOPSvdisks Data Rate

6. POOL PERFORMANCE IO & DATA RATE
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No throttling
NO Throttling set.

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mkthrottle -type mdiskgrp -bandwidth 250 -name MB_V7000_Pool -mdiskgrp 0
TOTAL PERFORMANCE ON SVC
MBps IOps
No difference with no throttle set on SVC. Reason: Current datarate is < Throttle

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Disabled the cache of the vdisks to see impact on V7000 (14:10)
TOTAL PERFORMANCE ON SVC
MBps IOps

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Performance on V7000 (14:10)
TOTAL PERFORMANCE ON SVC
MBps IOps

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Performance on SVC pools after disable cache on vdisks
TOTAL PERFORMANCE ON SVC
Disable Vdisk Cache

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
TOTAL PERFORMANCE ON SVC
MBps IOps

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
POOL PERFORMANCE TPC
Throttle

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
POOL PERFORMANCE TPC
V7000 pool MB Data Rate Read and Write (drops to 50MB read & 50MB write)

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
mkthrottle -type host -bandwidth 150 -name hostthrottle -host 1 (12:00 next day)
PERFORMANCE SVC (WITH 2 THROTTLES)
MBps IOps
IBM_2145:CG8_Cluster:johan>lsthrottle
throttle_id throttle_name object_id object_name throttle_type IOPs_limit bandwidth_limit_MB
0 MB_V7000_Pool 0 V7000_pool mdiskgrp 50
1 hostthrottle 1 Win2012 host 150

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
mkthrottle -type host -bandwidth 150 -name hostthrottle -host 1 (12:00 next day)
HOST PERFORMANCE TPC
Total Host Data Rate drops to 300MB = 150MB read & 150MB Write. So throttle of 150MB is no total.

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
mkthrottle -type host -bandwidth 150 -name hostthrottle -host 1 (12:00 next day)
VDISK PERFORMANCE TPC
Impact on vdisk with no throttle
No impact on vdisk with a throttle

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
mkthrottle -type host -bandwidth 150 -name hostthrottle -host 1 (12:00 next day)
VDISK PERFORMANCE TPC
As seen with vdisks: no impact on data rate on Pool where there is already a throttle defined
(V7000_pool) . Total is 300MB (150R & 150W)

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
mkthrottle -type host -bandwidth 150 -name hostthrottle -host 1 (12:00 next day)
mkthrottle -bandwidth 10 -type vdisk -vdisk 11 (vdisk in child pool without throttle)
SVC PERFORMANCE
MBps IOps
throttle_id throttle_name object_id object_name throttle_type IOPs_limit bandwidth_limit_MB
0 MB_V7000_Pool 0 V7000_pool mdiskgrp 50
1 hostthrottle 1 Win2012 host 150
2 throttle0 11 V7K_CP_Vdisk02 vdisk 10

19. V7000 Pool
SVC THROTTLING
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Scenario:
VDISK 9
CG8-vdisk
Win2012
wwpn
wwpn
V7000 Child Pool
VDISK 11
CG8-vdisk
Host
Throttle 50MB (pool)
Throttle 150MB
Throttle 10MB (vdisk)
In this case Data rate:
- 60MB read (50MB from V7000 Pool and 10MB from vdisk with throttle
- 60MB write (50MB from V7000 Pool and 10MB from vdisk with throttle
Host throttle does nothing
With no throttle at all:
- 227MB read
- 227MB write

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mkthrottle -type mdiskgrp -bandwidth 50 -name MB_V7000_Pool -mdiskgrp 0 (15:55)
mkthrottle -type host -bandwidth 150 -name hostthrottle -host 1 (12:00 next day)
mkthrottle -bandwidth 10 -type vdisk -vdisk 11 (vdisk in child pool without throttle)
SVC PERFORMANCE
MBps IOps
throttle_id throttle_name object_id object_name throttle_type IOPs_limit bandwidth_limit_MB
1 hostthrottle 1 Win2012 host 150
2 throttle0 11 V7K_CP_Vdisk02 vdisk 10

21. V7000 Pool
SVC THROTTLING
© 2015 E-Storage All rights reserved
Scenario:
VDISK 9
CG8-vdisk
Win2012
wwpn
wwpn
V7000 Child Pool
VDISK 11
CG8-vdisk
Host
No Throttle
Throttle 150MB
Throttle 10MB (vdisk)
In this case Data rate:
- 140MB read (130MB from V7000 Pool and 10MB from vdisk with throttle
- 140MB write (130MB from V7000 Pool and 10MB from vdisk with throttle
Looks like 150MB Host throttle kicks in.
With no throttle at all:
- 227MB read
- 227MB write

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IMPACT THROTTLE
Response time with no throttle defined
ReadWrite Latency 0-1 ms
mkthrottle -type host -bandwidth 20 -host 1
Read Write latency up to 12ms
Host has to wait longer before IO is handled.

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SET THROTTLE WITH GUI
In this document only CLI commands are used, but can also be done by using the GUI (except on Pools)
Bandwidth can be set in:
- MBps
- GBps
- TBps
- With a max of 256TBps
IOPS:
Valid values are 1 - 33554432